Plastic composition and method of making the same



Patented 22, 1935 UNITED STATES f l 2,018,492 I PLASTIC COMPOSITION AND METI IOD OF MAKING THE SAME Herman L. 'Grupe, Scotia, and Roy H. Kicnle,

Schenectady, N. Y., assignors to General Electric Company, a corporation of New York No Drawing.

9 Claims.

The present invention relates to plastic compositions and more particularly to a rubber-resin composition which is relatively unaffected by mineral oils and hydrocarbons and which is water, alkali and acid proof, and to methods of making the same.

Rubber is known to be a desirable material-for many applications where flexibility and elasticity as well as insulation is required. Due to these qualities it has been employed in various elec-' trical apparatus but a chief objection has been its attack by mineral oils commonly employed in such apparatus. When in contact with mineral oils, or with such hydrocarbons as naphtha, gasoline and the like, the rubber swells and distorts very easily due to attack by these chemical agents. It has been proposed to incorporate with the rubber such resins asthose of the phenolic type in order to increase theinsulation characteristics and in some cases the acid and alkaline resisting qualities of the rubber. However, as far as we are aware such resins have not materially en- Our invention will be best understood by-referrl'ng to the following detaileddescription thereof and its scope will be pointed out in the appended claims.

Alkyd resins, as .is known, include all those complexes resulting primarily from the reaction of a polyhydric alcohol, such as glycerine, and.

a polybasic acid, such as phthalic acidor its anhydride, with or without other reacting ingredients.

In accordance with one method of carrying out our invention an alkaline solution of an alkyd resin is prepared by heating, for example, 50 parts by weight of a glycerol-phthalate resin with 250 parts by volume of a5% ammonia solution. Equal parts by. weight of this solution and concentrated rubber latex, for example the material known as Revertex are thoroughly mixed, and to the mix ture is added a 5% solution of an acid, for example acetic acid. The precipitate is washed thoroughly with water to remove the excess acid and acetates formed in the reaction and is dried Application October 27, 1931, Serial No. 571,454

at a temperature between -85 C. It is then mixed on a rubber mill according to usual practice, with sulphur or other vulcanizing agent, accelerator and such fillers as desired. A suitable mixture, for. example, is the following. I

Parts by weight Rubber-alkyd resin composition 200 Sulphur I .3 ,Accelerator (Captax) 2 n Zinc oxide-- 50 The composition is vulcanized or cured in the regular way. A satisfactory cure is obtained when the composition is treated for example at approximately 140 C. for a period of about 3 1 hours.

Instead of using a straight alkyd resin, we may use a resin of the type modified-during its preparation with-fatty acids derived from vegetable oils, such as the drying oils, and/or the oils themselves. For example, an alkyd resin prepared from glycerine, phthalic anhydride and linseed oil fatty acids was employed by dissolving it in an ammoniacal solution and compounding it with latex as in the previous case. A vulcanized 25 composition was produced using the folio ingredients and proportions:

Parts by weight Rubber-fatty acid alkyd resin composi-' tion v 200 Sulphur 6 Accelerator (Captax) 1.5 Zinc oxide .1...... 10.0 Clay 7 100.0 35

A 3-hour cure at about C. was employed.

Tests on compositions such as those prepared as described above showed .that both the swelling and lateral expansion of the composition in both l0-'-C' transformer oil and 55 naphtha was reduced approximately 50% as compared to straight rubber composition prepared from the same in,- gredients without the resin.

it the flexibility of .the composition is to be 45 resins ismore fully described in the copending application of Kienle and Rohlis Serial No. 393,119, flled Sept. 16, 1929 and assigned to the assignee or the present invention.

As an example of the preparation of such a rubber-resin composition the following is given:

A resin is prepared by heating I v Parts by weight Glycerine.-. 92 I Phthalic anhydride 222 Ethylene glycol 93 Adipic acid 219 at the proper temperature to the requisite end.

point. For example, the ingredients are cooked at 190 C. to a 20 second cure on a 200 C. hot plate. This resin is a flexible type'oi alkyd resin in whichthemol ratio of glycerol phthalate to glycol adipate is 1 :3.

50 parts by weight of this resin is dissolved in ammonia water and mixed with 200 parts by Parts by weigh Resin-rubber mixture 200.0 Zinc oxide 10.0 Sulphur 10.0 Captax (accelerator) 2.5 Stearic a 2.0

The compound is mixed on a rubber mill according to usual rubber compounding practice and then cured in a press at 135 C. for 15 minutes.

In order to illustrate the invention further the 6 following additional examples are given showing how the resin may be varied in making the rubher-resin composition. I

A-A resin was prepared by cooking Parts by weight Glycerine 92 Adipic acid 219 at 190 C. to an second cure on a 200 C. hot plate.

B'-A resin was prepared by cooking Parts by weight Linseed oil acids 140 'Glycerine 101 Buccinic acid 166 at 190' c. to a is second cure on a 206' c.1101: plate.

C--A resin was prepared by cooking 4 Parts byv weight Phthalic anhydride.. 444- Ethylene glycol 186 at 190' C. until the mass was hard and brittle at room temperature.

solutionsv or suspensions were made with each of these resins by treating 50 parts byweight'oi the resin withammonia water.

Each of the solutions or suspensions was then mixed with rubber latex using a ratio of 200. parts by weight of rubber gumto 50 parts by weight of resin. The mixtures were each diluted with 2% ammoniawater then precipitated with a solution of 5% acetic acid. The precipitate was then thoroughly washed with waterand dried at C. for 12-14 hours. The dried resin-rubber mixture was compounded on a rubber mill prior to vulcanization using the following ingredients:

' Parts by weight 1. Resin A-rubber.mixture 200.0 Zinc oxide 10.0 Sulphur 10.0 Captaxv a 2.5 Stearic acid....- 2.0

l Parts by weight 2. Resin Brubber mixture 200.0 10 Zinc oxide 10.0 P-33 thermotomic carbon 400.0

Sulphur 10,0 Captax .1..... 2.5 Stearic acid 2.0 is Parts by weight 3. Resin C-+rubber mixture 200.0

Zinc oxide 10.0 Sulphm 10.0 Captax 2.5

. Stearic acid -1- 2.0

Thermotomic carbon was added in 2 to facilitate handling.

Each of the above compounds werecured in a 2| press 15, minutes at C.

By means of our invention there results a resin-rubber mixture wherein each rubber particle is in intimate association with a film of alkyd resin. Thus the rubber is carefully pro- U tected from attack by oils and hydrocarbons such as naphtha and gasoline by a thin film of alkyd resin. At the same time no material reduction in resiliency or other desirable physical properties oi the rubber is effected. On the contrary the rell siliency andelasticity of the rubber is maintained and in. some cases enhanced especially where the thin film oi alkyd resin protecting the individual particles of rubber is of the flexible type.

It is not necessary to employ a solution of the resin in making the rubber-resin composition.

- An emulsion of the resin may be used. For example, an emulsion may be made by emulsifying a mixture comprising 10 parts by weight of casein glue, 30 parts by weight of water and parts by weight of an alkyd-resin containing 13% by weight of linseed oil fatty acids and containing also 13% 'by weight of linseed oil. A mixture of approximately equal parts by weight of this emulsion and a suspension of rubber latex eon.

taining the iollowing is made:'

7 Parts by weight 1m! 120 China clay 30 Sulphur 5 l0 Accelerator 1 Water 150 Two pieces of aeroplane cloth wereimpregnated with this mixture, dried at room temperature and vulcanized together for 30 minutes at 100' C. in a vulcanizing press. The resulting piece of laminated material was pliable and withstood the action of mineral oil, fuel oil and a mixture of 68 naphtha and benzol, being only slightly .5

3,010,492 It is apparent that the various examples given above are merely illustrative of the invention. Within the scope of the invention are included various obvious modifications. It is to be understood that any suitable type of alkyd resin may be employed in carrying out the invention.-

The rubber-alkyd resin composition may be employed in connection with various flllers, dyes, pigments and the like and may be used either in suspension, solution or solid form. to make various articles of manufacture such as gaskets, oil-proof cloth, gasoline gauge diaphragms, wire coatings and other materials which must be flexible, elastic or pliable and resistant to mineral oils and hydrocarbons.

It is of course understood that in the curing operation, the alkyd resin where it is 0! the heat convertible type converts to. the lniusible, insoluble state. Where, as in the case of glycol phthalate, heretofore described, the resin is of the nonheat convertible type, the latter apparently becomes an integral part oi the vulcanized-rubber. What we claim as new and desire to secure by Letters Patent of the United'States, is:

1. 'A composition comprising an intimate mixture of discrete particles .oivulcanized rubber. and surface-coated with a flexible alkyd resin. i

2. A compositiomcomprising an intimate mixture of discrete particles of rubber surface-coated with a resin of the alkyd type.

3. An article oi manufacture comprising an oil resistant alkyd resin-rubber composition, said composition comprising vulcanized rubber particles surface-coated with a fllm o1 alkyd resin.

4. The methodoi makingan oil and gasoline alcohol and a dibasic aliphatic acid.

. and drying the precipitate formed, compounding said precipitate with vulcanizing agent,.accelerator and filler,.and curing the entire mass.

6. The method of making a vulcanizable composition capable of being cured to produce an oil and gasoline resistant product, which comprises preparing an emulsion 01' an alkyd resin, and

compounding said emulsion with rubber latex containing mixed therewith vulcanizing agent,'. accelerator and filler.

7. An oil and gasoline resistant composition comprising an intimate mixture oi discrete particles of rubber surface-coated with flexible a1- kyd resin which is the product of reaction of a polyhydric alcohol, a polybasic acid, a dihydric 8. A composition of matter comprising an intimate mixture of rubber latex and an aqueous dispersion of an alkyd resin. u

9. A composition of matter comprising an intimate mixture of rubber latex and an aqueous alkaline solution or an alkyd resin.

HERMAN L. GRUPE.

ROY H. KIENLE. 

